Lecture 6 2/1/24

Question 1

What are the general characteristics of Strongylida superfamily Trichostrongyloidea?

Answer 1

-males with caudal copulatory bursa
-buccal cavity with reduced/absent teeth
-thin-shelled, morula stage eggs
-most found in G.I. tract
-direct life cycles
-limited larval migration
-seen in ruminants, swine, horses, cats, birds, camelids
-pathogenic

Question 2

What size eggs are seen in Trichostrongyloidea?

Answer 2

60-108 um

Question 3

What are the characteristics of Trichostrongylus axei?

Answer 3

aka stomach worm, bankrupt worm, or black scour worm
-DH is cattle, sheep, goats, horses, swine, rabbits, people
-found in stomach
-females 3-8 mm
-males 2-6 mm
-PPP of 3 weeks

Question 4

How Trichostrongylus axei be identified?

Answer 4

-tiny worms
-no visible buccal cavity
-pointed head
-cervical indentation
-well developed bursa in male

Question 5

What are the characteristics of Trichostrongylus spp. except T. axei?

Answer 5

-intestinal worms
-DH is ruminants

Question 6

What are the characteristics of Ostertagia spp. in cattle and Teladorsagia spp. in sheep/goats?

Answer 6

-aka brown stomach worms
-DH is ruminants
-male 6-8 mm
-female 8-10 mm
-PPP of 3 weeks

Question 7

How can Ostertagia spp. be identified?

Answer 7

-tiny buccal cavity with no oral hook
-present cervical papillae
-small or no vulvular flap on female
-symmetrical dorsal lobe on male’s bursa
-caudal annulations on female

Question 8

What are the characteristics of Ostertagia spp. pathogenesis?

Answer 8

-in abomasum of ruminants
-parasitic larvae found in gastric glands
-cause parasitic gastritis and chronic abomasitis
-projectile diarrhea, emaciation, anemia, and edema/bottle jaw are common signs
-L3 overwinter on pastures and infect during grazing season

Question 9

What is type 1 ostertagiosis?

Answer 9

larvae mature directly to adults in abomasum without experiencing arrested development

Question 10

What is type 2 ostertagiosis?

Answer 10

larvae in arrested development become metabolically active and molt to the adult stage

Question 11

What are the characteristics of Haemonchus spp.?

Answer 11

-aka barber-pole worm
-DH is ruminants
-males 10-20 mm
-females 18-30 mm
-PPP is 2-3 weeks
-most important sheep/goat parasite
-can remove 1/5 of a lamb’s circulating erythrocytes in one day

Question 12

What are the recognition characteristics for Haemonchus spp.?

Answer 12

-found in abomasum
-white oviducts twisted around red gut in female
-large vulvular flap in female
-prominent cervical papillae
-oral hook in tiny buccal cavity
-asymmetrical flap and dorsal ray on male bursa

Question 13

Why are all life cycles of the Haemonchus spp. detrimental to the host?

Answer 13

all life stages suck blood

Question 14

What are the clinical signs of Haemonchus infection?

Answer 14

-anemia with PCV of 25% or less
-hypoproteinemia
-typically NO diarrhea

Question 15

Which three parasites are found in the abomasum of ruminants?

Answer 15

-Trichostrongylus axei
-Haemonchus spp.
-Ostertagia spp.

Question 16

What are the characteristics of Cooperia spp.?

Answer 16

-aka cattle bankrupt worm
-DH is ruminants
-male and female adults < 10 mm
-PPP of 2 weeks
-most common in cattle
-developing some drug resistance

Question 17

What are the characteristics of Nematodirus spp.?

Answer 17

-aka thread-necked intestinal worm
-DH is ruminants
-female 15-25 mm
-male 10-19 mm
-PPP of 3 weeks
-large, football shaped eggs, 200 um
-females only produce a few eggs per day

Question 18

What are the characteristics of Nematodirus infective stages?

Answer 18

-L3 develops in egg shell and hatches based on environmental stimuli
-L3 must undergo freezing before warm weather in order to hatch (N. battus)

Question 19

What are the goals of gastrointestinal nematode (GIN) control?

Answer 19

-contain GIN population below disease/production loss-causing levels
-reduce transmission
-reduce drug resistance
-support producer profitability

Question 20

Why is it important to NOT kill all of the adult parasites when controlling GINs?

Answer 20

killing all adults would leave the DH populations very susceptible to future infections

Question 21

What is resistance, in terms of parasites?

Answer 21

normal therapeutic dose is no longer effective in achieving >95% reduction in fecal egg counts

Question 22

How does resistance develop in parasites?

Answer 22

-too frequent deworming
-underdosing
-treating all animals instead of need-based treatment
-treating and moving to a clean pasture - only resistant parasites in the new pasture

Question 23

How can GIN infections be limited?

Answer 23

-avoid overstocking
-separate young animals from adults ASAP
-feed animals in dry lot
-prevent manure contamination of feed and water
-remove manure often
-provide clean, disinfected/non-infected areas for births
-use selective treatment
-feed well balanced rations

Question 24

What are the characteristics of the FAMACHA system?

Answer 24

-regular color checks of the mucus membranes of sheep/goat eyes (every 2-3 weeks)
-paleness indicates anemia from blood loss
-treatment based on anemia estimate
-only used for assessing Haemonchus infection